This application claims the priority of German Application 199 41 087.9, filed Aug. 30, 1999, the disclosures of which are expressly incorporated by reference herein.
The present invention relates to a hinged joint in roof systems of vehicles with adjustable roof, and more particularly, to a hinged joint with first and second bearings held together by a bearing pin.
In movable roof systems for vehicles, for example folding tops for convertible vehicles, hinged joints are installed between hinged arms of the roof system frame as described in DE 295 16 619 U1. These joints consist of a bearing pin held on an articulated arm that is guided in a bearing seat of the other articulated arm. The quality of the hinged joints must satisfy high demands since the frame is exposed to high mechanical stress and the influences of weather and must have the same service life as the vehicle.
To reduce joint friction, the hinged joints are generally built in such a way that the bearing pin is surrounded by a bearing bushing that consists of a very low friction material, frequently with a PTFE coating. The bearing bushing thus provides for the bearing pin to move without friction in the bearing mount.
The bearing bushing increases the weight and the costs of the hinged joint. In addition, the manufacturing effort for the hinged joint increases disproportionately greatly with the number of hinged components. With an increasing number of hinged components, the risk also increases that during manufacturing or in operation one of the components will become dysfunctional because of mechanical stress. In particular, the plastic bearing bushings must be able to withstand fairly high bearing forces within permissible wear limits, which makes great care necessary with respect to material selection and manufacturing.
DE 42 16 557 A1 and DE 42 16 559 C2 disclose a ball element in a swivel bearing, which is supported against the housing of the swivel bearing by a guide ring, wherein a friction-reducing surface coating is provided on the surface areas of the ball element and guide ring that are turned toward each other. These documents do not give more specific data on the friction-reducing surface coatings with regard to material selection and thickness of the coating, in particular for use in adjustable vehicle roofs.